How to install a vessel sink.

I have a glass vessel sink that I want to install above counter, with a mounting ring between the glass bowl and the counter. The problem I have is that the threaded part on the pop-up drain that came with the sink is not long enough. (Below is a picture of the drain. Note that the mounting ring is not shown on the picture.) The counter is 1.75 inch thick. The threaded part does not stick out underneath the counter, so I cannot tighten the nut to secure the sink.

I have been to numerous plumbing stores to look for a drain that has longer thread, but could not find one. Does anyone know of a drain that works with a thick counter top?

The guy in one store confused me even more. He said that the nut should be tightened against the mounting ring, not against the underside of the counter. In that case, the thread is long enough, but how would I secure the sink to the vanity so it is stable?

So here's what I did. I made the hole in the slate slightly bigger, so that the nut fits in (see pic.) I tightened the nut against the mounting ring. The mounting ring sits on the counter, the nut is hidden underneath. Once I'm sure it's all water tight, I might caulk the gap between the tail piece and the counter from underneath, for added stability.

I thought it easier to resurrect this thread than start a new one for the same problem. Now that vessel sinks are more common are there extensions or extra-long drains available that will allow the nut to be secured to the underside of the vanity top (tightened against backer board, not wood), rather than the method in the diagram?

If there is nothing readily available and the diagrammed method is used, is the nut just tightened all the way up to the mounting ring before it is set into the hollow in the slate (tile/thinset/backerboard in my case)? Can this method even be used for tile or it only works with a thicker slab like slate or stone? How is the entire thing secured (eg should the nut be set into thinset, silicone, something else?)?

The "mounting ring" is supposed to be a cushion between the sink and counter, NOT between the nut and the sink. But if you did use it as a "gasket" it should have had a metal washer between it and the nut.